Recent Physics Results from the National Spherical Torus Experiment (NSTX) Presented by: Jonathan E. Menard, PPPL For the NSTX Research Team 21 st IAEA/Fusion 2006 Meeting Oct 16 – 21, 2006 Chengdu, China Supported by Office of Science Culham Sci Ctr U St. Andrews York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAERI Hebrew U Ioffe Inst RRC Kurchatov Inst TRINITI KBSI KAIST ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep U Quebec College W&M Colorado Sch Mines Columbia U Comp-X General Atomics INEL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U Old Dominion U ORNL PPPL PSI Princeton U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Maryland U Rochester U Washington U Wisconsin
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Recent Physics Results from the National Spherical Torus Experiment (NSTX) Presented by: Jonathan E. Menard, PPPL For the NSTX Research Team 21 st IAEA/Fusion.
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Recent Physics Results from the National Spherical Torus Experiment (NSTX)
Presented by:Jonathan E. Menard, PPPL
For the NSTX Research Team
21st IAEA/Fusion 2006 MeetingOct 16 – 21, 2006Chengdu, China
M.G. Bell 1), R.E. Bell 1), J.M. Bialek 2), J.A. Boedo 3), C.E. Bush 4), N.A. Crocker 5), S. Diem 1), C.W. Domier 6), D.A. D’Ippolito 7), J.R. Ferron 8), E.D. Fredrickson 1),
D.A. Gates 1), K.W. Hill 1), J.C. Hosea 1), S.M. Kaye 1), C.E. Kessel 1), S. Kubota 5),H.W. Kugel 1), B.P. LeBlanc 1), K.C. Lee 6), F.M. Levinton 9), N.C. Luhmann, Jr. 6), R. Maingi 4), D.K. Mansfield 1), R.P. Majeski 1) R.J. Maqueda 9), E. Mazzucato 1),
S.S. Medley 1), D. Mueller 1), J.R. Myra 7), H.K. Park 1), S.F. Paul 1), W.A. Peebles 5), R. Raman 10), S.A. Sabbagh 2), C.H. Skinner 1), D.R. Smith 1), A.C. Sontag 2),
V.A. Soukhanovskii 11), B.C. Stratton 1), D. Stutman 12), G. Taylor 1), K. Tritz 12), J.R. Wilson 1), H. Yuh 9), W. Zhu 2), S.J. Zweben 1), and NSTX Research Team
1) Princeton Plasma Physics Laboratory, Princeton, NJ, USA2) Columbia University, New York, NY, USA3) University of California - San Diego, La Jolla, CA, USA4) Oak Ridge National Laboratory, Oak Ridge, TN, USA5) University of California - Los Angeles, Los Angeles, CA, USA6) University of California - Davis, Davis, CA, USA7) Lodestar Research Corporation, Boulder, CO, USA8) General Atomics, San Diego, CA, USA9) Nova Photonics Incorporated, Princeton, NJ, USA10) University of Washington, Seattle, WA, USA11) Lawrence Livermore National Laboratory, Livermore, CA, USA12) Johns Hopkins University, Baltimore, MD, USA
Thanks to many contributors to this presentation:
3IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal
confinement science in support of ITER and future ST’s
• Integrated High Performance
• Macroscopic Stability
• Transport and Turbulence
• Boundary Physics
• Energetic Particle Physics
• Plasma Start-up and Ramp-up
4IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal
confinement science in support of ITER and future ST’s
• Integrated High Performance
• Macroscopic Stability
• Transport and Turbulence
• Boundary Physics
• Energetic Particle Physics
• Plasma Start-up and Ramp-up
5IAEA 2006 - NSTX Overview – J. Menard
NSTX plasmas approach the normalized performance levels needed for a Spherical Torus - Component Test Facility (ST-CTF)
ST-CTF goal: neutron flux = 1-4MW/m2
A=1.5, = 3, R0 = 1.2m, IP= 8-12MA, N ~ 5, HH=1.3,
T = 15-25%, fBS=45-50%
Peng et al, PPCF 47, B263 (2005)
Bootstrap
Fraction
6IAEA 2006 - NSTX Overview – J. Menard
High performance can be sustained for several current redistribution times at high non-inductive current fraction
• p and NBI current drive provide up to 65% of plasma current Relative to 2004, High N H89P now sustained 2 longer
116313G12
TRANSP non-inductive current fractions
D. Gates, PoP 13, 056122 (2006)D. Gates – Poster EX/P1-3 Tue PM
7IAEA 2006 - NSTX Overview – J. Menard
MHD-induced redistribution of NBI current drive contributes to NSTX “hybrid”-like scenario as proposed for ITER
• High anomalous fast ion transport needed to explain neutron rate discrepancy during n=1
• Fast ion transport converts peaked JNBI to flat or hollow profile
• Redistribution of NBICD makes predictions consistent with MSE
J. Menard, PRL 97, 095002 (2006)n=1 mode onset
S. Medley – Poster EX/P6-13 Fri AM
• qMIN > 1 for entire discharge, increases during late n=1 quasi-interchange activity
n=1 mode onset
8IAEA 2006 - NSTX Overview – J. Menard
Very high elongation at low li opens possibility of higher P and fBS operation at high T
Divertor coil upgrade2004 2005
Vertically stable
operating space
li
121241
t=275ms
= 3.0, X= 0.8li = 0.45
Vertically
unstable
fNI=100%
target
Gates, et al., PoP 13 (2006) 056122.Gates, et al., NF 46 (2006) 17.
• Sustained 2.8 (reached = 3) for many WALL using rtEFIT isoflux control– Allowed by divertor coil upgrade in 2005, no in-vessel vertical position control coils
• Stability analysis of new operational regime under investigation• High research important for CTF design studies
D. Gates – Poster EX/P1-3 Tue PM
9IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal
confinement science in support of ITER and future ST’s
• Integrated High Performance
• Macroscopic Stability
• Transport and Turbulence
• Boundary Physics
• Energetic Particle Physics
• Plasma Start-up and Ramp-up
10IAEA 2006 - NSTX Overview – J. Menard
2.01.51.00.50.0 R (m)
-2
-1
0
1
2
120047t = 0.745s
Bru
Bpu
Brl
Bpl
6 midplanecontrolcoils
Z (
m)
Stabilizer plates• Dynamic error field correction (DEFC)
• pressure-driven RFA increases damping at high-beta– Included in calculations– Based on applied field, or
DCON computed mode spectrum
• Viable physics for simulations of plasma rotation in future devices (ITER, CTF, KSTAR)
appliedfieldonly
axis
t = 0.370s
116939With RFA
With RFA(DCON)
n = 1field
Zhu, et al., PRL 96 (2006) 225002.Columbia U. thesis dissertation
A. Sontag – Oral EX/7-2Rb Fri AM
12IAEA 2006 - NSTX Overview – J. Menard
RWM actively stabilized at ITER-relevant low rotation for 90/RWM
• Plasma rotation reduced by non-resonant n = 3 magnetic braking– Non-resonant braking to
accurately determine n=1 RWM critical rotation
• First demonstration of low- RWM control at low A– Exceeds DCON N
no-wall for n = 1 and n = 2
– n = 2 RWM amplitude increases, mode remains stable while n = 1 stabilized
– n = 2 internal plasma mode seen in some cases
Sabbagh, et al., PRL 97 (2006) 045004.
0.40 0.50 0.60 0.70 0.80 0.90t(s)
0.00.51.01.52.0
05
10152005
1015200.00.51.01.5
02468
Shot 120047
0
2
4
6
N
IA (kA)
Bpun=1 (G)
Bpun=2 (G)
/2 (kHz)
N > N (n=1)no-wall
120047120712
< crit
92 x (1/RWM )
6420840
1.51.00.50.02010
02010
0
t(s)0.4 0.5 0.6 0.7 0.8 0.9
S. Sabbagh – Submitted post-deadline
13IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal
confinement science in support of ITER and future ST’s
• Integrated High Performance
• Macroscopic Stability
• Transport and Turbulence
• Boundary Physics
• Energetic Particle Physics
• Plasma Start-up and Ramp-up
14IAEA 2006 - NSTX Overview – J. Menard
Dedicated H-mode confinement scaling experiments measure scaling trends that differ from high-A results
Stronger dependence on BT :
E-98y,2 BT0.15 E-NSTX BT
0.85-0.9
Electrons responsible for BT dependence
HH98y,2 ~ 0.9 → 1.1 → 1.4
4 MW
HH98y,2 ~ 1.4 → 1.3 → 1.1
Weaker dependence on IP : E-98y,2 IP
0.93 E-NSTX IP0.4
Ions responsible for IP dependence
4 MW
NSTX E exhibits strong IP scaling at fixed q:
E-98y,2 IP1.1 E-NSTX IP
1.3-1.5NSTX Transport Physics:
S. Kaye – Oral EX/8-6 Fri PM
15IAEA 2006 - NSTX Overview – J. Menard
Pellet-induced temperature perturbations show that electron transport response depends strongly on equilibrium conditions
• H-mode, monotonic q()– Exhibits very stiff profile
behavior
– Critical Te gradient
• L-mode, reversed shear– Core Te increases while
edge Te decreases
– No apparent critical temperature gradient
2-color soft X-ray array diagnoses fast Te and Te response to lithium pellet injection
R / LTe
t=297→301 ms
R / LTe
t=440→444 ms
Stutman, et al., to be published in PoP
16IAEA 2006 - NSTX Overview – J. Menard
Tangential microwave scattering system aiding in testing leading theories of anomalous electron transport
Scattering system measures reduced n/n from upper ITG/TEM to ETG kr
ranges during H-mode
i at neoclassical level during H-mode
ELMs lin >> ExB during L-phase for all ks
lin << ExB during H-phase for ITG/TEMlin ~ ExB during H-phase for ETG
GS2 calculations indicate lower linear growth rates at all wavenumbers during H-mode: ETG unstable
Non-linear GTC ITG stable during H-mode
121283
17IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal
confinement science in support of ITER and future ST’s
• Integrated High Performance
• Macroscopic Stability
• Transport and Turbulence
• Boundary Physics
• Energetic Particle Physics
• Plasma Start-up and Ramp-up
18IAEA 2006 - NSTX Overview – J. Menard
Experiments utilizing advanced shape control and parametric scans find ELM stability sensitive function of edge parameters
• Control of ELM size critical issue for ITER• Access to small-ELM regime sensitive function of magnetic topology
• ELM type also depends on global N & pedestal electron collisionality– Predicted to impact pedestal JBS, access to ballooning second stability– Recent results find Type V also accessible at low
• ITER will operate in new, small * regime for fast ion transport– k ≈ 1 means "short" wavelength Alfvén modes– Fast ion transport expected from interaction of many modes– NSTX can access multi-mode regime via high fast / total and vfast / vAlfven
NSTX accesses ITER-relevant fast-ion phase-space island overlap regime with full diagnostic coverage – including MSE
E. Fredrickson, Phys. Plasmas 13, 056109 (2006)
0
1
2
3
4
5
6
0.0 0.2 0.4 0.6 0.8
CTF
ARIES-ST
NSTXITER
fast(0) / tot (0)
Vfa
st/
VA
lfvé
n
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0.0 0.2 0.4 0.6 0.8
CTF
ARIES-ST
NSTXITER
fast(0) / tot (0)
Vfa
st/
VA
lfvé
nS. Medley – Poster EX/P6-13 Fri AM
23IAEA 2006 - NSTX Overview – J. Menard
Reflectometry data reveals 3-wave coupling of distinct fast-ion instabilities for first time
Influence of toroidal localization of TAE mode energy on fast
ion transport and EPM/TAE stability presently being investigated
Bi-coherence analysis reveals 3-wave coupling between 1 EPM and 2 TAE modes
N. Crocker, Phys. Rev. Lett. 97, 045002 (2006)
EPM Energetic Particle Mode
TAE Toroidal Alfven Eigenmode
24IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal
confinement science in support of ITER and future ST’s
• Integrated High Performance
• Macroscopic Stability
• Transport and Turbulence
• Boundary Physics
• Energetic Particle Physics
• Plasma Start-up and Ramp-up
25IAEA 2006 - NSTX Overview – J. Menard
Coaxial Helicity Injection (CHI) has convincingly demonstrated the formation of closed poloidal flux at high plasma current
3. Once IINJ 0, reconstructions track dynamics of detachment & decay
1. IP=160kA remains after CHI injector current ICHI 0 at t=9ms
2. After t=9ms, plasma current decays away inductively
Evidence for high-IP flux closure:
R. Raman, PRL (2006), accepted for publication R. Raman – Poster EX/P8-16 Sat AM
26IAEA 2006 - NSTX Overview – J. Menard
High-harmonic fast waves (HHFW) and electron Bernstein waves (EBW) being explored for low-IP heating and IP ramp-up
• Goal: IP ramp-up of CHI plasma with HHFW-CD & BS overdrive
• Recent discovery: In CD phasing, electron heating efficiency doubled by increasing BT=0.45T 0.55T– Reduced parametric decay instabilities– Reduced surface wave excitation
• Achieved high Te=3.6keV with HHFW in CD phasing for first time– Near NSTX record Te of 4keV– Achieved at highest BT = 5.5kG– Can heat low-Te = 200eV target plasma
EBW emission measurements with steerable radiometer: Measure up to 90% BXO conversion efficiency Potential for efficient heating and CDHighest in L-mode, poorer apparent coupling in H-mode
D. Gates – Poster EX/P1-3 Tue PM
B = 5.5 kG
4.5 kG
0
10
20
30
40
50
0.1 0.2 0.3 0.4 0.5Time (sec)
Ele
ctr
on
En
erg
y (
kJ)
PRF= 2 MW
=25ms
20ms
27IAEA 2006 - NSTX Overview – J. Menard
NSTX is strongly contributing to fundamental toroidal confinement science in support of ITER and future ST’s